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Dissection and Flat-mounting of the Threespine Stickleback Branchial Skeleton
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パンデリクシス (Panderichthys) の胸と指の起源について
Catherine A Boisvert1, Elga Mark-Kurik, Per E Ahlberg
1Subdepartment of Evolutionary Organismal Biology, Department of Physiology and Developmental Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden. catherine.boisvert@ebc.uu.se
Nature
|September 23, 2008
まとめ
化石の分析により,四足類 (四肢を持つ脊椎動物) の指は,先行して存在していた魚の羽根の半径から進化したものであり,進化の新奇物ではないことが明らかになった. この発見は,脊椎動物の四肢の進化に関する以前の仮定に異議を唱える.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- 比較解剖学 比較解剖学とは
背景:
- テトラポッドの指は決定的な特徴ですが,魚のからの進化的起源は議論の余地があります.
- 以前の研究では,魚の finn 骨格に直接的な同値が欠如し,部分的に Panderichthys 化石の解釈による数字がノベルティであることを示唆しました.
研究 の 目的:
- パンデリクシス (Panderichthys) の胸骨格を高度なイメージングを用いて再検査する.
- 魚の finn ラディアルとテトラポッドの桁の間のホモロジーを調査するために.
- 魚から四足類への肢体の進化の軌道を明らかにする.
主な方法:
- 高解像度コンピュータトモグラフィー (CT) スキャニングで,不動のパンデリクシスの胸をスキャンする.
- 様々な魚群 (アクチノプテリジアン,サメ,肺魚) のの発達を比較分析した.
- 以前の化石の再構築と発達遺伝子のデータの再評価.
主要な成果:
- CTスキャンは,以前のパンデリクシスの再構築における""が人工物であり,遠端の放射球が存在することを明らかにしました.
- パンデリクシス (Panderichthys) のディスタルフィン骨格は,これまで理解されていたよりも大きな四足類のような特徴を示しており,ティクタアリック (Tiktaalik) よりもさらに大きい.
- 既存の遠端半径は,サルコプテリジアン魚で識別可能であり,指の指紋の同質的な起源を示唆しています.
結論:
- 数字はテトラポッドに限った進化の新奇物ではない.
- 指と足の指は,サーコプテリジアン (ロブ finned) 魚で見つかった事前のディスタル放射線から派生しています.
- この研究は,魚のフィン・ラディアルとテトラポッドの指の間のホモロジーの有力な証拠を提供し,脊椎動物の四肢の進化に関する私たちの理解を洗練しています.
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